1. Technical Field
Embodiments of the present invention relate to a vehicle, and in particular to a vehicle provided with a secondary air supply passage for supplying air to an exhaust passage of an internal combustion engine.
2. Background Art
In an internal combustion engine for a straddle-type vehicle such as a motorcycle, a secondary air supply passage for supplying air to an exhaust passage may be arranged as an exhaust emission control device. Such an arrangement is described, for example, in Japanese Unexamined Patent Publication No. 2007-40250. In the described arrangement, a one-way reed valve is disposed in the secondary air supply passage. The reed valve functions in the following manner: when pressure in the exhaust passage is made negative by an exhaust pulsating pressure produced in the exhaust passage, the reed valve opens to vent or pass air; on the other hand, when the pressure in the exhaust passage is made positive, the reed valve closes to stop venting or passing the air. In other words, the reed valve is a device that opens or closes, according to the pulsation of exhaust gas, to send air (secondary air) to the exhaust passage for cleaning the exhaust gas.